Indoor radon (222Rn) and thoron (220Rn) measurements and assessment of human risk in the dwellings of Tiruchirappalli city (Tamil Nadu, India)

Indoor radon and thoron measurements were carried out in 92 dwellings of Tiruchirappalli city employing single entry pin-hole dosimeter with a solid state nuclear track detector for a period of one year covering all four seasons. The results indicated that the indoor radon and thoron concentrations varied dynamically throughout the year. The maximum mean indoor radon concentration (42.1 ± 20 Bq m−3) and thoron concentration (98.2 ± 23 Bq m−3) were registered during monsoon season and minimum mean radon concentration (26.1 ± 14.5 Bq m−3) and thoron concentration (36.6 ± 18.8 Bq m−3) during pre monsoon season. Indoor radon and thoron concentrations are directly related to the types of building materials, ventilation rate and atmospheric temperature. The mean indoor radon concentration was 33.2 Bq m−3 which was within the safe limit of 300 Bq m−3 as set by WHO. Hence this study concluded that the indoor radon and thoron concentrations in the studied region did not pose any radiological hazard to dwellers.

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